The launch marks the second time Google has upgraded a business program this week - a week when Microsoft awaits a response to its bid to buy Yahoo Inc. in an attempt to undermine Google's dominance of Internet search and advertising.

Microsoft's unsolicited bid, initially valued at $44.6 billion, is backed largely by money the company has made selling software.

Google has been giving consumers, students and businesses free access to competing software hosted over the Web in a concept known as "cloud computing."

More than 500,000 businesses have signed up to use Google's applications, according to figures to be released Thursday by the Mountain View-based company. Some businesses pay $50 extra per user for a souped-up version of the applications, but the fees so far account for only a sliver of Google's $16.6 billion in annual revenue.

Google last year collected $181 million for software sales and other services besides online advertising.